This section provides background information related to the present disclosure which is not necessarily prior art.
Such intermediate circuits are generally used for space and cost reasons instead of intermediate circuits having a single larger capacitor.
Intermediate circuits of electric motors are checked for malfunction in the context of a failure simulation, which takes place for product certification and for checking compliance in the sense of the low voltage guideline. Here, for example, the effects of a failure of a capacitor are also verified by means of a short-circuit in the capacitor that has failed. Due to the short-circuit of a capacitor in the series connection, an excess voltage occurs over the remaining series-connected capacitors. Under some circumstances, this leads to a bursting of a capacitor, and the electrolyte material of the burst capacitor that is released as a result is dispersed in particular on the conductor plate of the intermediate circuit. The conductor plate of the intermediate circuit comprises a base insulation for the required insulation between the network circuit and contactable metal parts, which prevents the risk of an electric shock. As a result of the electrolyte accumulation in the area of the base insulation of the conductor plate, tracking between the power supply circuit and contactable metal parts is increased, and a high-voltage test in the context of the verification of the compliance with the low voltage guideline can no longer be passed successfully. Therefore, the fault simulation has a negative result.
In the case of known intermediate circuits, a bursting of the capacitors is prevented, for example, by additional fuses connected in series before the component. However, fuses arranged before the component respond due to an excess current, and thus only when the bursting capacitor causes this high current, so that the capacitor in some cases still can burst. Fuses for the high direct-current voltages in the intermediate circuit moreover are quite large and they also cause relatively high costs. Alternatively or additionally, in known intermediate circuits, a dispersing of electrolyte material is prevented by a special encapsulation of the capacitors. An encapsulation on a conductor plate is expensive and it causes additional costs, and, depending on the circuit, it cannot be implemented so that the electrolyte does not reach any other region of the circuit. These solutions are complicated, cost intensive and they require a relatively large installation space.